.cavern-runner{display:flex;flex-direction:column;align-items:center;gap:0.75rem;
    width:100%;max-width:1024px;margin-inline:auto;
    font-family:ui-monospace,"Cascadia Mono","Courier New",monospace;}
  .cavern-runner .cr-screen{width:100%;max-height:78vh;aspect-ratio:4/3;display:block;
    image-rendering:pixelated;background:#000;border:0.5rem solid #00d7d7;box-sizing:border-box;
    touch-action:none;cursor:pointer;}
  .cavern-runner .cr-screen:focus-visible{outline:3px solid #00d7d7;outline-offset:3px}
  .cavern-runner .cr-pad{display:none;gap:0.5rem;width:100%}
  .cavern-runner .cr-pad button{flex:1;padding:1rem 0;font:inherit;font-size:1.25rem;
    background:#202020;color:#d7d7d7;border:2px solid #555;border-radius:0.5rem;
    touch-action:none;-webkit-user-select:none;user-select:none;}
  .cavern-runner .cr-pad button:active{background:#00d7d7;color:#000}
  .cavern-runner .cr-pad button:focus-visible{outline:2px solid #00d7d7;outline-offset:2px}
  @media (pointer:coarse){.cavern-runner .cr-pad{display:flex}}
  /* the Spectrum's four-colour flash, as the machine's badge */
  .cavern-runner .cr-flash{display:flex;width:100%;justify-content:flex-end;gap:0}
  .cavern-runner .cr-flash i{width:1.75rem;height:0.375rem}
  .cavern-runner .cr-flash i:nth-child(1){background:#ff0000}
  .cavern-runner .cr-flash i:nth-child(2){background:#ffff00}
  .cavern-runner .cr-flash i:nth-child(3){background:#00ff00}
  .cavern-runner .cr-flash i:nth-child(4){background:#00ffff}
  .cavern-runner .cr-hint{margin:0;font-size:0.75rem;letter-spacing:0.08em;
    text-align:center;opacity:0.65;}